


Experiments in Xenobiology

by thescyfychannel



Category: Homestuck
Genre: Hemospectrum, Hemospectrum Kink, M/M, Non-Human Genitalia, Seadwelling Trolls (Homestuck), Troll Genitalia (Homestuck), Xeno
Language: English
Status: Completed
Published: 2019-07-23
Updated: 2019-07-23
Packaged: 2020-07-11 17:20:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,757
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19931695
Author URL: https://archiveofourown.org/users/thescyfychannel/pseuds/thescyfychannel
Summary: One great beauty of large gaps in caste is the inevitable culture shock when The Full Sex occurs.That, or, the inevitably astounding orgasms.





	Experiments in Xenobiology

**Author's Note:**

  * For [FindingZ](https://archiveofourown.org/users/FindingZ/gifts).



> "I've always liked the headcanon that seadwellers have different anatomy than the rest of the troll casts....and of course that applies to their sexy bits too. This is a pretty vague prompt on purpose -- I'd love to see Eridan and Karkat getting together for the first time (mutual pining? dancing around each other like idiots for ages? anyone?) and exploring each others bodies and just generally having a really great time.
> 
> \+ bonus points if the differences somehow are *just* right for the other and make the orgasms strong and aplenty"

"Oh you have _got_ to be fucking _kidding me_."

Karkat Vantas is quite possibly the sexiest troll you've ever seen. Everything about him, from the broad spread of his shoulders to the deep timbre of his voice, draw you to him in a way that makes you contemplate quadrantal equations from now until the end of your godsdamn time.

Of course, when he's staring at you and your bulge like you're the weirdest thing you've ever seen, the hotness quotient tends to go down a fair bit.

"Look, Kar, I don't suppose you—"

"No," he says, and you clamp your mouth shut, as if you're afraid of what his reaction might be. "No, do _not_ speak, I do not want to hear you say any shit of any sort. Understood?"

"But _Kar_ —"

" _No._ "

You go silent for a few seconds longer, as he stares at your bulge and nook, his hands pressed together like some kind of heathen at pray. If mind could affect matter, you'd think he'd maybe burn a hole right through your body—but then again, most of Kar's staring tends to feel like that. Usually it'd make you feel like the very dead center of his world, but tonight, well.

" _Kar._ "

"Okay. Okay, fine! Say whatever it is you have to say, then shut the fuck up and let me _think_."

If you've only got a few seconds to speak, you're going to make it brief and prompt. You draw yourself up like a ruffled bird and fix him with your best glare, then say: "Listen, you don't see me sayin shit about the parts a your anatomy I consider to be odd or curious, so what the fuck gives you the liberty to go on givin me crap about mine?"

"It's _frilled_ , Eridan. What the fuck!"

"Well yours has those weird...thins on it! Multiple weird thins!" Your fins do a flare out, and you cross your arms over your chest to avoid the urge to protectively cup your bulge. "This isn't doin much good for my self-esteem, I hope you know."

"We were going to have _sex_ , Ampora, if your self-esteem hasn't gotten knocked right the fuck out of the park on that fact alone, we're going to have to have a talk about what you're doing to _my_ self-esteem."

Okay. You'll give him that one. But grudgingly, and still with the overwhelming urge to protect your bits. "Fine, I guess. Look, just. Think a it as one a those...interestin sex toys, or somethin. Or _you_ can use your bulge, I'll ride you—"

"No, nope, fuck no," he tells you, and your expression has barely half a second to fall before he follows it up with: "If I'm using your nook for the very first time, I want to be in _full_ control."

"...is that because you're worried about it bein 'weird' by landdweller standards too?"

"Shut up and spread it, Ampora," he says, and you decide to assume that regardless of what his facial expression currently is, you're going to have sex and it is going to be absolutely fucking _great_. "Next round, I'll ride you, if your weirdass bulge hasn't tired itself out."

Never mind. You might not even make it to having sex, because you're pretty damn sure you're gonna kill him. "Kar—"

And that's where you cut off, because that's _when_ he decides to shove his equally weirdass bulge _in_. While yours is a beautifully constructed mass of carefully and delicately crafted seadweller concupiscent parts, his is covered in weirdly soft spines that are almost reminiscent of the nubs he calls horns. On his way in, each of them rubs up against the insides of your nook, and you half turn over to clutch at the bedsheets, moaning, and on his way _out_ , well.

Karkat does a thing with his bulge, and you'd complain about how his abbreviated attempt at an exit is just bad manners and a sign that he's not going to be able to give your nook the proper pounding it deserves, but _then_ the soft spines drag against you even harder, practically locking your best friend into place, and you nearly _scream_. "Figured you'd like that," he murmurs, running a hand over your stomach and side, just barely nudging your gills. "Alright, if you're gonna squirm like that, fine."

Fine? Fine what? You have no idea what's going on, but your answer comes when he shifts you around enough to get one of his knees braced on the bed, one of your legs tugged up close against your chest, and you, well, half-sprawled on your side with your face in the sheets. Inside you, his bulge coils and thrashes, and he keeps doing that odd, bucking-rocking thing that makes you choke, fucking you hard as he can with a limited range of motion. It's driving you absolutely insane, and you think he's maybe getting off on that, on the way you twist and squirm on him, on the way you try to press down and pull off all at once, on the twist and scrap of his bulge inside your nook—

"Come _on_ ," he growls, and at first, you think he's talking to you—and then you feel him _flex_ inside of you, and the spine-nubs do a weird thing (they...flatten out, maybe?) and he pulls all the way out of you and _slams_ back in, and, oh, oh, _oh_ , oh _fuck_ , it's as good you imagined it would be, _he's_ as good as you thought he would be, and he's fucking you so hard you can barely stand it. Another brief round of tug of war between his spines and your nook ensues before he decides to have a second go at the flex thing, and this time, it makes you keen. You're tightening up hard every time he moves, and he looks likely to take thorough advantage if you so much as let him. "So _now_ you decide to shut up? I'm, ah—fucking _offended_ here, Ampora."

There's not much else you can do besides scream, but at least you get your fangs and face and tongue to cooperate enough that it's his name you scream. He looks pleased, at least, by the sound (and you think maybe sight) of you, and that's about when you lose all your focus because he shifts you _again_ , onto your stomach, then sort of your knees (or as much of them as you can get under you) when he hoists your ass into the air to bear down again.

It might've been easier to focus if he didn't follow it up with a hand wrapped around one of your horns and two fingers in your mouth, tracing over the points of your teeth, a pleased purr building up in the back of his throat. "You're so godsdamn pretty, Ampora. You know that, right? Pretty and needy and _tight_."

Words. You're good at words. You're supposed to say some more words to him, right? But he's fucking into you again, and all you can think to actually do is _keen_ , so, maybe that's a no on the words? Surely he won't mind if you can't say anything, not with that heat of his building inside your nook, not when all you want to do is let him take you until you can't think of a single deeps damn thing.

Another flick of his bulge sends every inch of your body into a kind of shock, and you wonder if he's noticed that the curving frills are an internal thing—it's a brief moment of lucid thought before pleasure crashes down on you like a tidal wave, breaking just after its peak, and you spill violet—or, you would, it Karkat's bulge didn't keep it trapped deep. At first, it's a very, _very_ welcome thing—then his grip tightens on your horn, and it's _his_ turn to keen, and you're suddenly far too full of far too much slurry, far too aware of each spurt and leak, of the sudden violet-crimson-colored sheen of it coating your thighs.

You desperately wish you had room to be embarrassed, but your bulge _writhes_ at the heat, and Kar's proving himself to have almost as much stamina as a troll born at sea. He pulls out of you, and you feel him grip your hip, intending to roll you to your back and ride you.

Oh, _hell_ no.

Battle tactics are still your bread and butter, and when he has a go at flipping you over, you roll with the motion, arm coming up to grab at him as well. It's the work of a single moment and simple twist to get him sprawled on his back, startled and flushed, and the work of another couple to twist your bulge right up between those legs, drag it across that puffy little nook, dripping wet and ready for you. "Bright fuckin red," you tell him, and drag a finger through the slurry. "Matches your face."

"Eridan!" It's about all you're willing to let him get out before you shove your "weirdass bulge" inside, delicate frills and all, and your impatience is well worth it to watch _him_ choke, to feel his body tighten and spasm around you. 

Hm. Seems you'd hit up against everything just right to make him nigh-instantly come.

As pretty a sight as it is, you have little patience to stay still and watch the red slurry spread. Instead, you press down, all but pinning his shoulders to his knees as you roll your hips, deeper and deeper. Under you, he comes apart, and you cover him with kisses as he does, the burning heat of him wrapping itself around you until you bury yourself deep in him for a final time.

You think it might drag out his fifth (or sixth, possibly seventh) orgasm, from the way he tightens and keens, but the scant space left between you is too much of a mess of violet-tinted-almost-pink to be sure, and you're too much of a mess to care beyond the slow burn of pride putting the flare back into your fins.

"Not bad," you murmur, lips brushing over the curve of his ear, and Karkat, exhausted though he is, has the nerve to bite you. "Ow, _fuck_. See if I let you ride my weirdass bulge next time—"

"Shut it," he grumbles, shifting himself sideways to wrap around you. "You'd be begging for me and you know it."

Well. You can't exactly argue with that.


End file.
